Re: [Caml-list] Recursive types and functors.

[David Brown <caml-list@davidb.org>]

On Wed, Mar 26, 2003 at 09:25:13AM +0100, Jean-Christophe Filliatre wrote:

> A (too) naive solution could be  to make a polymorphic instance of the
> Set module (either  by adding an argument 'a  everywhere in signatures
> OrderedType  and S,  or  by  copying the  functor  body and  replacing
> Ord.compare by compare); then you have polymorphic sets, say 'a Set.t,
> balanced using compare, and you can define

Actually, my real case doesn't use sets, but a dynamic array
implementation I made myself.  I originally needed a functor because I
needed an empty value to fill in past the used elements of the real
array.

What I ended up doing was filling in those elements with 'Obj.magic 0'.
I don't really like walking outside of the type system, but since I
never return them, I don't think it will be a problem.

I still may try to figure out how to do it with the multiple functor
approach, just so to learn how to do it.

Thanks,
Dave

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